I needed a couple of "sand bags" to stabilize my lightstands. I was trying to talk my wife into fabricating a couple from the lens of old blue jeans. However I found these bags on eBay which I bought at two for ten dollars with free shipping.
http://www.ebay.com/itm/160898016999...84.m1497.l2649
They are well made and seem quite sturdy. My wife says that there is no way she could buy the nylon and zippers for these bags and make them for five dollars each.
I don't actually use sand in these weight bags. I use pea gravel instead. The gravel is heavier and won't ruin gear if it leaks.